Providing credentials to a service, whether via a mobile or other device, is often a tedious experience for a user. Unfortunately, to make authentication easier for themselves, users will often engage in practices such as password re-use, and/or the selection of poor quality passwords, which render their credentials less secure against attacks. Accordingly, improvements in authentication techniques would be desirable. Further, it would be desirable for such improvements to be widely deployable, including on existing/legacy systems.